This application claims priority of Taiwan Application No. 90207753, filed on May 11, 2001.
1. Field of the Invention
The invention relates to a latch assembly, more particularly to a latch assembly that is adapted to be mounted on a recessed door of a cabinet, such as a fuse cabinet, for closing the same.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional latch assembly is shown to include a casing 10, a coupler shaft 24, a latch member 30, a pair of fastener nuts 33, a locking plate 28, an urging member 27, a pivot pin 25, and a lever 21.
As illustrated, the casing 10 is mounted on a recessed door P of a cabinet (not shown) via a U-shaped bracket 41 and a mounting bolt 42, includes a peripheral wall 101 defining a lever chamber 11 and having a front open end 109 for access to the lever chamber 11. The casing 10 further includes a rear wall 102 confining a rear side of the lever chamber 11, and a spring-confining flange 103 that projects rearwardly from the rear wall 102 to define a spring chamber 105. The rear wall 102 is formed with a shaft-extension hole 102xe2x80x3 in spatial communication with the spring chamber 105 and the lever chamber 11.
The coupler shaft 24 extends in a longitudinal direction, is disposed movably and rotatably in the casing 10, and passes through the shaft-extension hole 102xe2x80x3 in the rear wall 102. The coupler shaft 24 has a threaded portion 242 that is disposed outwardly and rearwardly of the spring chamber 105, and a pivot portion 241 that extends into the lever chamber 11 and that is formed with a pin-hole 241xe2x80x3. The coupler shaft 24 is rotatable about an axis.
The latch member 30 has a coupler portion 31 that is formed with a threaded shaft hole 311 for extension of the threaded portion 242 of the coupler shaft 24 therethrough. The threaded shaft hole 311 is confined by a threaded inner face that threadedly engages the threaded portion 242 of the coupler shaft 24. The nuts 33 are disposed at two opposite sides of the coupler portion 31 of the latch member 30 via two washers 32, and threadedly engage the threaded portion 242 of the coupler shaft 24 so as to secure the latch member 30 on the coupler shaft 24 and so as to permit co-rotation of the latch member 30 and the coupler shaft 24 about the axis and co-movement of the latch member 30 and the coupler shaft 24 in the longitudinal direction.
The locking plate 28 is fastened securely to the pivot portion 241 of the coupler shaft 24 via a fastener nut 29 for co-movement with the coupler shaft 24 in the longitudinal direction between an engaging position, in which, the locking plate 28 extends into the spring chamber 105 and releasably engages the flange 103, thereby preventing rotation of the coupler shaft 24 about the axis in the spring chamber 105, and a disengaging position, in which, the locking plate 28 moves outwardly of the spring chamber 105 to disengage from the flange 103, thereby permitting rotation of the coupler shaft 24 about the axis.
The urging member 27 is disposed in the spring chamber 105 for constantly urging the locking plate 28 and the coupler shaft 24 to move away from the spring chamber 105.
The pivot pin 25 is disposed in the lever chamber 11, and extends in a transverse direction relative to the longitudinal direction, and through the pin-hole 241xe2x80x3 in the coupler shaft 24.
The lever 21 extends in a vertical direction transverse to the longitudinal direction, and has a U-shaped pivot end 210 that projects into the lever chamber 11 and that has a pair of lugs 211 which confine a gap therebetween for receiving the pivot portion 241 of the coupler shaft 24 and which are formed with two opposing pivot slots 212 for extension of the pivot pin 25 therethrough. The lever 21 further has an operating end 213 that is opposite to the pivot end 210. Each of the pivot slots 212 is confined by a slot-confining wall that has a rear end generally aligned with the pin-hole 241xe2x80x3 in the coupler shaft 24 such that the pivot pin 25 constantly abuts against the rear ends of the slot-confining walls of the pivot slots 212 by virtue of urging action of the urging member 27. The lever 21 is turnable manually about the pivot pin 25 to a first position, as best shown in FIG. 2, in which, the operating end 213 of the lever 21 abuts against the casing 10 by virtue of the urging action of the urging member 27 to prevent rearward movement of the locking plate 28 and the coupler shaft 24 from the engaging position to the disengaging position in the longitudinal direction, thereby preventing rotation of the latch member 30 via the coupler shaft 24 in the spring chamber 105. The lever 21 is turnable manually about the pivot pin 25 to a second position, in which, the operating end 213 of the lever 21 turns outwardly and forwardly of the casing 10 and the pivot end 210 of the lever 21 turns rearwardly and downwardly toward the rear wall 102, thereby permitting rearward movement of the locking plate 28 and the coupler shaft 24 from the engaging position to the disengaging position. As such, co-rotation of the coupler shaft 24 and the latch member 30 about the axis is permitted.
A connecting member 23 includes a U-shaped portion 230 which is interposed between the pivot end 210 of the lever 21 and the pivot portion 241 of the coupler shaft 24 and which permits extension of the pin 25 therethrough. A tension spring 22 is interposed between the lever 21 and the connecting member 23 in such a manner that two opposite ends of the spring 22 resiliently abut against the lever 21 and the connecting member 23 so as to prevent change of relative positions of the connecting member 23 and the lever 21 when the lever 21 turns about the pivot pin 25 between the first and second positions.
During assembly of the aforesaid conventional latch assembly, it is inconvenient and laborious to mount the coupler portion 31 of the latch member 30 on the threaded portion 242 of the coupler shaft 24 at a desired position by virtue of threaded engagement between the inner threaded face of the latch member 30 and the threaded portion 242 of the coupler shaft 24. Moreover, the nuts 33 tend to loosen after a period of use, which may result in downward turning of the latch member 30 due to gravity, thereby unlocking the recessed door.
The object of this invention is to provide a latch assembly that can overcome the drawbacks associated with the pivot art.
Accordingly, a latch assembly of the present invention is adapted to be mounted on a recessed door, and includes a casing, a coupler shaft, a latch member, a pair of nuts, a locking plate, an urging member, a pivot pin, and a lever. The casing is adapted to be fixed on the recessed door, and includes a peripheral wall defining a lever chamber and having a front open end for access to the lever chamber, and a rear wall that confines a rear side of the lever chamber. The casing further includes a spring-confining flange that projects rearwardly from the rear wall to define a spring chamber. The rear wall is formed with a shaft-extension hole in spatial communication with the spring chamber and the lever chamber. The coupler shaft extends in a longitudinal direction, is disposed movably and rotatably in the casing, and passes through the shaft-extension hole in the rear wall. The coupler shaft has a threaded portion that is disposed outwardly and rearwardly of the spring chamber, a pivot portion that extends into the lever chamber, and that is formed with a pin-hole, and a mounting portion between the threaded and pivot portions. The threaded portion has a terminating end distal from the pivot portion and formed with a pair of axially aligned grooves that extend from the terminating end toward the mounting portion of the coupler shaft. The coupler shaft is rotatable about an axis. The latch member has a coupler portion that is formed with a shaft hole for extension of the threaded portion of the coupler shaft therethrough, and that has a hole-confining wall confining the shaft hole. The coupler portion of the latch member is further formed with a pair of engaging tongues that extend inwardly and radially from the hole-confining wall and that slidably and respectively engage the axially aligned grooves in the coupler shaft so as to permit sliding movement of the latch member along the length of the coupler shaft and so as to facilitate mounting and removal of the latch member on and from the coupler shaft. The nuts are disposed at two opposite sides of the coupler portion of the latch member, and threadedly engage the threaded portion of the coupler shaft so as to secure the latch member to the coupler shaft and so as to permit co-rotation of the latch member and the coupler shaft about the axis and co-movement of the latch member and the coupler shaft in the longitudinal direction. The locking plate is fastened securely to the mounting portion of the coupler shaft for co-movement with the coupler shaft in the longitudinal direction between an engaging position, in which, the locking plate extends into the spring chamber and releasably engages the flange, thereby preventing rotation of the coupler shaft about the axis in the spring chamber, and a disengaging position, in which, the locking plate moves outwardly from the spring chamber to disengage from the flange, thereby permitting rotation of the coupler shaft about the axis. The urging member is disposed in the spring chamber for constantly urging the locking plate and the coupler shaft to move away from the spring chamber. The pivot pin is disposed in the lever chamber, and extends in a transverse direction relative to the longitudinal direction through the pin-hole in the coupler shaft. The lever extends in a vertical direction transverse to the longitudinal direction, and is disposed outwardly and forwardly of the lever chamber. The lever has a U-shaped pivot end that projects into the lever chamber and that has a pair of lugs which confine a gap therebetween for receiving the pivot portion of the coupler shaft and which are formed with two opposing pivot slots for extension of the pivot pin therethrough. The lever further has an operating end that is opposite to the pivot end. Each of the pivot slots is being confined by a slot-confining wall that has a rear end generally aligned with the pin-hole in the coupler shaft such that the pivot pin constantly abuts against the rear ends of the slot-confining walls of the pivot slots by virtue of urging action of the urging member. The lever is manually turnable about the pivot pin between a first position, in which, the operating end of the lever abuts against the casing by virtue of the urging action of the urging member to prevent rearward movement of the locking plate and the coupler shaft from the engaging position to the disengaging position in the longitudinal direction, thereby preventing rotation of the latch member via the coupler shaft, and a second position, in which, the operating end of the lever turns outwardly and forwardly of the casing and the pivot end of the lever turns rearwardly and downwardly toward the rear wall so as to permit rearward movement of the locking plate and the coupler shaft from the engaging position to the disengaging position, thereby permitting co-rotation of the coupler shaft and the latch member about the axis.